Interconnect Surface Inspection Using Polarized Reflection Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in inspecting the top-layer metal of a redistribution layer in integrated circuits is the difficulty in distinguishing its distribution from the underlying-layer metal due to light penetration through dielectric layers, resulting in indistinguishable reflection intensities.
Innovation Solution
A method and device utilizing polarization light to differentiate between light signals reflected from the top and underlying metal layers by exploiting depolarization effects, based on intensity differences in light signals with distinct polarization states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light inspection is used to inspect the top-layer metal, then the inspection process is simple, but the reflection intensities from top-layer and underlying-layer metal become indistinguishable due to light penetration through dielectric layers
Solution Approach 1:
The patent changes the polarization state parameter of the incident light to differentiate between reflections from top-layer and underlying-layer metal. By using polarized light at specific angles and analyzing the polarization state of reflected light, the system can distinguish between the two metal layers based on their different polarization characteristics, thereby improving measurement precision without requiring complex additional hardware beyond standard polarization optics.
2Measurement precision
If polarization light inspection is used to differentiate between metal layers, then the discrimination accuracy improves, but the inspection device complexity increases
Solution Approach 1:
The patent applies partial polarization analysis by selecting specific polarization angles and analyzing only the relevant polarization components of reflected light. Instead of analyzing all polarization states comprehensively, the system uses a simplified approach by measuring light intensity at specific polarization angles, which is sufficient to differentiate between metal layers while reducing device complexity and computational requirements.
3Ease of operation
If light intensity analysis is used to detect metal distribution, then the inspection process is straightforward, but the ability to distinguish between top-layer and underlying-layer metal is lost
Solution Approach 1:
The patent introduces polarization state as an intermediary parameter to carry information about which metal layer the reflected light originates from. By encoding layer identification information in the polarization state of reflected light, the system maintains operational simplicity while preserving metal layer distribution information, as the polarization analysis provides a direct indicator of the reflecting layer without requiring complex additional measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately determines the planar pattern of the top-layer metal by distinguishing between light signals reflected from the surface and inner metal layers, reducing errors in inspection and enhancing the accuracy of the inspection process.
Implementation Method 1
illuminating a surface of an interconnect structure by an incident light having a first polarization state
Implementation Method 2
receiving a plurality of light signals reflected from the interconnect structure and having a second polarization state different from the first polarization state
Data Source
AI summary
A method and device of inspecting a surface of an interconnect structure are provided. The interconnect structure includes a first metal layer, second metal layer, and dielectric layer enclosing the second metal layer. The first metal layer and dielectric layer are disposed above the second metal layer. At least one portion of the first metal layer is exposed from the surface of the interconnect structure. The method includes: illuminating a surface of an interconnect structure by an incident light having a first polarization state; receiving light signals reflected from the interconnect structure and having a second polarization state different from the first polarization state; and determining a planar pattern of the first metal layer by differentiating between at least one light signal reflected from the first metal layer and at least one light signal reflected from the second metal layer according to intensity differences between the light signals.